I wouldn't mess with the spine. If you start trying to equalize the wear you'll wind up flattening it even more and that will upset the angle which will make it very difficult to properly hone. I think that some razors are beyond hope (unless your Bruno) and to me when there is extreme spine wear and especially if its uneven or there is warping of the blade its beyond what I'm willing to invest in a typical vintage blade.

I working on one now that has wear like you are describing luckily its a wedge, which are a bit more forgiving but I won't spend days honing to try and compensate for all the wear.If I can't get it shaving rite quick it will just go into the "drawer of shame".